Activity coefficients for NaBr in ethanol-water mixtures at 25�C (original) (raw)
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Journal of Electroanalytical Chemistry, 1998
The electrical conductivity of NaBr solutions and the emf of the cell: glass electrode (Na)NaBrAgBrAg in mixtures of water with propan-2-ol in the range 0-80 wt.% have been measured at 298.15 K. The values of limiting molar conductance (\ 0), association constants (K A), and the parameter of distance of ions (R) were obtained with the Fuoss-Justice equation. From the conductivity data obtained, the values of the Walden products (\ 0 p) were also calculated. The values of the Gibbs energy of transfer (Z t G 0) of NaBr from the water to the mixtures of water with propan-2-ol mixtures were obtained from the emf data. The dependencies of viscosity (p), limiting molar conductance (\ 0), Walden products (\ 0 p), association constants (K A) and the Gibbs energy of transfer (Z t G 0) of NaBr versus the mixed solvent composition have been discussed. The obtained results were compared with those obtained earlier for sodium chloride and iodide.
Activity Coefficients for NaCl in Ethanol-Water Mixtures at 25°C
Reccived J anuary 4, J 988; Revised /l.pril J, 1988 /l.clivily coe[ficienl valucs for NaCI in elhanol·waler mixtures cOn/aining 20,40,60, "70, 80 and 90 wcighl % e¡hallol are calculaled from ¡hc ernffor Ihe galvanic cell N a-glass I NaCl (m), 1/ 2 0 (lOO-Y) , ELOII (Y), /l.gCl I/l.g in which ¡hc weigh¡ % of ¡he corresponrlinl? solvenl is indicaled in paren· Ihc.l'cs. 'f'he resulls oblaincd are a!lalyzcd by using differenl Iheorclical models. Chernir:al morlels which lake i!ll o accounl Ihe pre.\'ence 01 ion pairs in solutio!ls 01 high elhwwl conlad are also used. Thcrc is goor! agrccmcnl betwccn Ihe rcsulls oblained from all Ihe m odel.\'.
Activity Coefficients of NaBr in Aqueous Mixtures with High Relative Permittivity Cosolvent: Ethylene Carbonate + Water at 298.15 K, 2010
The mean ionic activity coefficients of NaBr were experimentally determined in ethylene carbonate (EC) + water at 298.15 K from potential difference measurements of the following electrochemical cell containing two ion-selective electrodes (ISEs): Na-ISE|NaBr(m), EC(w), H 2 O(1-w)|Br-ISE The molality (m) varied between 0.04 mol · kg-1 and almost saturation, while the mass fraction of EC in the mixture (w) was varied between 0 and 0.8 in 0.1 unit steps. Values of the standard potential difference, E 0 (molal scale), were determined using a routine method of extrapolation together with the extended Debye-Hückel, Pitzer-Rard-Archer, and Scatchard equations. The results obtained produced good internal consistency, within the normal limits of experimental error in these types of measurement. Once E 0 was determined, the mean ionic activity coefficients of NaBr (γ), the Gibbs energy of transfer of the NaBr from the water to the EC + water mixture (∆G t 0), the standard solubility product of NaBr in EC + water (K sp 0), the NaBr primary hydration number (n hyd), Gibbs energy interaction parameters (g EN), and the salting constant (k S) were estimated. The results were comparatively analyzed with those of NaF and NaCl previously obtained in similar mixtures.
Activity Coefficients of LiCl in Ethanol−Water Mixtures at 298.15 K
Industrial & Engineering Chemistry Research, 2008
The electromotive force, E, of the cell containing two ion-selective electrodes (ISE) Na-ISE | LiCl(m), ethanol (Y), H 2 O(100-Y) | Cl-ISE has been measured at a temperature of 298.15 K as a function of the weight percentage Y of ethanol in a mixed solvent. Y was varied between 0 and 80% in 20-unit steps, and the molality of the electrolyte (m) was between 0.02 and 4 mol kg -1 , approximately. This electrode system was previously checked and calibrated by measuring the activity coefficients of LiCl in 0, 20, and 40% methanol-water and comparing them with literature values. The values of the standard electromotive force, E 0 (molal scale), were determined using routine methods of extrapolation (Debye-Hückel and Pitzer equations). The results obtained produced good internal consistency within the normal limits of experimental error encountered in these types of measurements. Once E 0 was determined, the mean ionic activity coefficients for LiCl, the free energy of transfer from the water to the alcohol-water mixture, and the primary LiCl hydration number were calculated. The variation of these magnitudes with the composition of the mixture is discussed in terms of the ionsolvent and ion-ion interactions and their changes with the properties of the medium.
Fluid Phase Equilibria, 1995
We have determined the activity coefficients for NaC1 in NaC1 + NaForO + NaAcO + HeO and NaC1 + NaForO + NaPrO + H20 mixtures, and for NaBr in the NaBr + NaForO + NaAcO + H20 mixture (ForO = Formate, AcO = Acetate and PrO = Propionate). The studies were performed by the emf method and at 25 °C. The analysis of the experimental data was accomplished through a Reilly-Wood-Robinson type treatment, by replacing the Friedman parameters by the /-dependence functions defined by the Scatchard, Pitzer and Lim models. The methodology used consisted of introducing the binary interaction parameters, obtained from previous studies of the corresponding ternary mixtures NaX + NaY + H20 (X: CI or Br; Y: ForO, AcO or PRO), into the equations for the quaternary system. In the present paper, the binary interaction parameters corresponding to the mixture NaCI + NaForO + H20 have been more accurately re-determined. The data thus obtained from the use of the different models were compared to each other. The mixing parameters for the NaForO + NaAcO + H20 and NaForO + NaPrO + H20 ternary systems were also determined as ionic strength functions.
Effect of pressure on conductance. IV. Ionic association and Walden products in ethanol
The Journal of Physical Chemistry, 1967
The conductance at 30" of sodium bromide in methanol and in ethanol, under pressures up to 500 atm, were measured in the concentration range 3 5 104c 5 20. Confirming previous (1) Grateful acknowledgment is made for the support of this work by the Directorate of Chemical Sciences, Air Force Office of Scientific
Activity Measurements in the Ternary System NaBr + NaCIO4 + H20 at 25
Activity measurements in the ternary system NaBr + NaClO4 + H2O at 25°C , 1996
The activity coefficients of sodium bromide in the ternary system NaBr + NaCI04 + 1t20 were determined at 25~ and constant ionic strength of O.1, 0.5, 1, 2, and 3 mol-kg-1 from emf of the cell without liquid junction 1SE-Na I NaBr(ma), NaCIO4(mB), AgCl~s) I Ag The experimental activity coefficients were comparatively analyzed by using the Harned, Scatchard, Pitzer and Lim-HOLL treatments. All these methods are adequate for the analysis of the experimental data. The results have been compared with those of Lanier for the system: NaCl + NaCI04 + 1t20. The Gibbs excess energy of mixing was obtained and qualitatively interpreted in terms of ionic interactions.
Journal of Chemical & Engineering Data, 2011
The mean ionic activity coefficients of NaBr were experimentally determined in formamide + water mixtures at 298.15 K from potential difference measurements of the following electrochemical cell containing two ion selective electrodes (ISEs): Na-ISE|NaBr (m), formamide (w), H 2 O (1Àw)|Br-ISE. The molality (m) varied between 0.02 mol 3 kg À1 and almost saturation, whereas the mass fraction of formamide in the mixture (w) was varied between 0 and 1 in 0.1-unit steps. The determination of E 0 * (molal scale) was carried out following a method similar to that proposed by Hitchcock and using the classical extended DebyeÀH€ uckel and Scatchard equations. We also use for this purpose a modification of the Pitzer equation proposed by Rard and Archer and the most recent modified three-characteristic-parameter-correlation model. The results obtained produced good internal consistency, within the normal limits of experimental error in these types of measurement. Once E 0 * was determined, the mean ionic activity coefficients of NaBr (γ), the Gibbs energy of transfer of the NaBr from the water to the formamide + water mixture (ΔG t 0 ), standard solubility product of NaBr in formamide + water (K sp 0 ), and NaBr primary hydration number (n hyd ) were estimated. The results were comparatively analyzed with those of NaF and NaCl previously obtained in similar mixtures.
Transference Number Measurements for LiBr in Ethanol-Water Mixtures at 25°C
Transference numbers for bol h lons of LlSr in elhanol-waler mixtures up lo 85 wt % ethanol at 25 oC are obtalned. The experimental tachnlque usad for these measurarnents Is the dlrect movlng boundary. These transference numbers, after the volume and the solvent correetlons are applled, are optlmlzed Irom the unlly value of thelr sum at eaeh eoneentratlon studled and the T_ values obtalned. Afterward these optlmlzed translerenee number values are also usad to optlmlze the eoneentratlon valua C bea! for the dlfferenl LISr solutlons used. The extrapolatlon of these Tbea! to zero eoncentratlon values to flnd the IImlllng transferenee number values, T O , Is made by uslng the 1963 Fuoss and Onsager electrophoretle termo These T O values are analyzed wlth respeet to the ehange of Ihe ethanol eontent of the medium. Finally, lonle IImlting conduetance values are determined. 1ntroduction The use of mixed solvents is a common practice to study the properties of electrolytes in solution. In fact, the important changes the ion-solvent interaction undergoes as a conse quence of the competitive presence of two solvents in the medium leads to important structural alterations in both the solvated ions and the medium, which can be analyzed by means of the changes that occur in both the thermodynamic and the transport properties of the ions present in the solution. From among such mixed solvents, the water-organic solvents ha ve been extensively used due to the high solubility that ena bies such studies to be extended to a wide concentration range for a large group of electrolytes. Nevertheless, the determi nation of transport parameters in these media has received no special attention from researchers, and only a small number of these transport parameters are collected in the literature. In the present paper, transference numbers for both ions of LiBr in ethanol-water mixtures, up to 85 wt % ethanol are reported. One of the main difficulties encounterad was meas uring accurately the concentration of the LiBr solutions usad. However, the experimental determination of such transference numbers independently for both the anion and the cation avoided this difficulty by optimizing them and afterward optim izing also the solution concentration.